Process of treating leather and fibrous material with polyisocyanate derivatives



United States Patent 3,493,426 PROCESS OF TREATING LEATHER AND FI- BROUSMATERIAL WITH POLYISOCYANATE DERIVATIVES Mai-wan R. Kamal, Minneapolis,Minn., assignor to General Mills, Inc., a corporation of Delaware NoDrawing. Filed Jan. 3, 1967, Ser. No. 606,584 Int. Cl. B44d 1/32; D06m3/00 I ll R(CH-3) NCON=C i: L y

R2 x prepared by reacting oximes of l to ll carbon atoms and polymericfat acid polyisocyanates, aqueous emulsions of such compounds and aprocess of treating leather and fibrous materials with such compounds.

The present invention relates to novel derivatives of certainpolyisocyanates and to the use of such derivatives in the treating ofleather and fibrous materials. More particularly, it relates to novelderivatives of polyisocyanates prepared from polymeric fat acids andcertain oximes and to the process of treating leather and fibrousmaterials with said derivatives.

It has recently been discovered that polyisocyanates prepared frompolymeric fat acids can be used to treat leather and fibrous materialsto give same unexpectedly improved physical properies. Such treatmentimproves the softness and water repellency of the leather and fibrousmaterials. Additionally, tear resistance and wrinkle resistance isimproved in many instances.

The noted polyisocyanates have been applied to the leather and fibrousmaterials using organic solvents or aqueous emulsions. Neither of theseprocedures is completely free of difficulties. Thus, the solventselected must be inert to isocyanate groups and must be removed at thecompletion of the contacting or impregnating of the leather or fibrousmaterial. Flammability and other hazards characteristic of many organicsolvents are also encountered. Aqueous emulsions of the saidpolyisocyanates were found to be quite useful. The polymeric fat acidpolyisocyanates are only very slowly reactive toward water and,accordingly, there is no great loss of isocyanate groups in the limitedperiod of time that the aqueous emulsion is formed and applied. Butthere is a loss of isocyanate groups and the emulsion can, therefore, beprepared only a reasonably short period of time prior to use.

It is an object of my invention to provide novel derivatives of certainoximes and polyisocyanates prepared from polymeric fat acids. Anotherobject of the invention is to provide novel aqueous emulsions of suchderivatives which are stable for relatively long periods of time atambient temperatures. A further object of the invention is to provide anovel process of treating leather and fibrous materials with suchderivatives. These and other objects will become apparent from thefolowing detailed description.

I have now discovered that oximes having from 1 to about ll carbon atomscan be reacted with the polymeric fat acid polyisocyanates to producenew compounds having outstanding properties. These neW compounds can beused in the preparation of aqueous emulsions which can be stored forlong periods of time at ambient temperatures. The emulsions can be usedto treat leather and fibrous materials to obtain the unexpectedly fineproper- 3,493,426 Patented Feb. 3, 1970 ties obtained with the polymericfat acid polyisocyanates per se.

The polyisocyanates employed in the preparation of the derivatives ofthe present invention have the following idealized, structural formula:

[nj gonpmool where y is O or 1, x is an integer of 2 to about 4 and R isthe hydrocarbon group of polymeric fat acids.

The polyisocyanates wherein y is O are prepared by converting thepolymeric fat acids to the corresponding polymeric acid chlorides,reacting the acid chlorides with a metal azide to form the polymericacyl azides and then heating the acyl azides to produce thepolyisocyanates. This method of preparation can be convenientlyillustrated by the following equations (using a dimeric fat acid as anexample):

The polyisocyanates wherein is l are prepared by converting thepolymeric fat acids to the corresponding polynitriles and thenhydrogenating the polynitriles in the presence of ammonia and a catalystsuch as Ramey nickel to form polyamines. The polyamines are then reactedWith phosgene to give the polyisocyanates. This method of preparationcan be conveniently illustrated by the following equations (using adimeric fat acid as an example):

The polymeric fat acids, useful as the starting materials for preparingthe polyisocyanates, are prepared by polymerizing a fat acid. The termfat acid as used herein refers to naturally occurring and syntheticmonobasic aliphatic acids having hydrocarbon chains of 824 carbon atoms.The term fat acids, therefore, includes saturated, ethylenicallyunsaturated and acetylenically unsaturated acids. Polymeric fat radicalis generic to the divalent, trivalent and polyvalent hydrocarbonradicals of dimerized fat acids, trimerized fat acids and higherpolymers of fat acids, respectively. These divalent and trivalentradicals are referred to herein as dimeric fat radical and trimeric fatradical.

The saturated, ethylenically unsaturated, and acetylenically unsaturatedfat acids are generally polymerized by somewhat different techniques,but because of the functional similarity of the polymerization products,they all are generally referred to as polymeric fat acids.

Saturated fat acids are difficult to polymerize, but polymerization canbe obtained at elevated temperatures with a peroxidic reagent such asdi-t-butyl peroxide. Because of the low yields of polymeric products,these mate rials are not commercially significant. Suitable saturatedfat acids include branched and straight chain acids such as caprylicacid, pelargonic acid, capric acid, lauric acid, myristic acid, palmiticacid, isopalmitic acid, stearic acid, arachidic acid, behenic acid andlignoceric acid.

The ethylenically unsaturated acids are much more readily polymerized.Catalytic or non-catalytic polymerization techniques can be employed.The non-catalytic polymerization generally requires a highertemperature.

Suitable agents for the polymerization include acid or alkaline clays,di-t-butyl peroxide, boron trifluoride and other Lewis acids,anthraquinone, sulfur dioxide and the like. Suitable monomers includethe branched and straight chain, polyand monoethylenically unsaturatedacids such as 3-octenoic acid, ll-dodecenoic acid, linderic acid,lauroleic acid, myristoleic acid, tsuzuic acid, palrnitoleic acid,petroselinic acid, oleic acid, elaidic acid, vaccenic acid, gadoleicacid, cetoleic acid, nervonic acid, linoleic acid, linolenic acid,eleostearic acid, hiragonic acid, moroctic acid, timnodonic acid,eicosatetraenoic acid, nisinic acid, scoliodonic acid and chaulmoogricacid.

Acetylenically unsaturated fat acids, such as isanic and isanolic acids,can also be polymerized to give polymeric acids which can be used. Theacetylenically unsaturated acids occur only rarely in nature and areexpensive to synthesize. Therefore, they are not currently of commercialsignificance.

Although any one of the above-described saturated, ethylenicallyunsaturated and acetylenically unsaturated fat acids may be used toprepare the polymeric fat acids, it is generally the practice in the artto polymerize mixtures of acids (or the simple aliphatic alcoholestersi.e., the methyl esters) derived from the naturally occurringdrying and semi-drying oils. Suitable drying and semi-drying oilsinclude soybean, linseed, tall, rung, perilla, oiticia, cottonseed,corn, sunflower, dehydrated castor oil and the like. Also, the mostreadily available acids are oleic and linoleic and thus they arepreferred starting materials for the preparation of the polymeric fatacids. It is preferred to employ as starting materials in thepreparation of the polyisocyanates, relatively pure dimerized fat acids.Such acids can be obtained from mixtures containing monomer, thedimerized fat acids, trimerized fat acids and higher polymers by highvacuum distillation or solvent extraction. The use of relatively puredimerized fat acids as a starting material is advantageous where adiisocyanate of high purity is desired. Of course, mixtures of thepolymerized fat acids can also be used to prepare mixtures ofpolyisocyanates. Any of the described unsaturated polymeric fat acidscan be hydrogenated prior to the use thereof in the polyisocyanatepreparation.

The following examples illustrate the preparation of the polyisocyanatesuseful in the present invention.

EXAMPLE A In a 1 liter, round bottom flask equipped with a refluxcondenser protected by a calcium chloride drying tube were placed 200 g.of purified dimerized fat acid dissolved in 200 ml. of Skellysolve B and65 g. of phosphorus trichloride. The dimerized fat acid was derived fromthe mixture of acids in tall oil and consisted mainly of dimerizedlinoleic and oleic acids. It had the following properties: wt. percentdimerized fat acid-99; wt. percent monomer0.5; neut. equiv.286; and sap.equiv. 280. The reaction mixture was heated under reflux for 2 hours andthen allowed to stand overnight. The clear solution of the dimerized fatacid chloride was decanted from the heavy phosphorus acid. The solventand excess phosphorus trichloride were removed under reduced pressure.

Into a 1 liter reaction flask equipped with cooling coils, stirrer andthermocouple was placed a solution of 30.4 g. sodium azide in 125 ml.water cooled to C. To this rapidly stirred solution was added a solutionof 100 g. of the dimerized fat acid chloride dissolved in 150 ml. ofacetone. The reaction temperature was controlled at 10-15 C. during theaddition and during a 1 hour period following addition, after which 200m1. of heptane was added. The heptane layer was separated, washed with 2portions of cold Water, and then dried over magnesium sulfate. To 200m1. heptane maintained at 65-70 C. was added the above dried heptanesolution of the dimerized fat acyl azide. The solution was maintained ata temperature of 65-70 C. for 1 hour and then the heptane was evaporatedat reduced pressure. There was obtained 70 g. liquid diisocyanate havingthe following formula:

Where D is the dimeric fat radical derived from the starting dimerizedfat acids.

EXAMPLE B The preparation as described in Example A was repeated exceptthat the dimerized fat acid chloride (94 g.) was dissolved in ml. ofheptane instead of acetone. There was obtained 63 g. of thediisocyanate.

EXAMPLE C The preparation as described in Example A was repeated exceptthat 213 g. of the dimerized fat acid chloride was dissolved in 300 ml.acetone. There was obtained 177 g. of the diisocyanate.

EXAMPLE D Two hundred forty grams of phosgene (2.42 mole) were dissolvedin 700 ml. of dry toluene with cooling in an ice bath to maintain thesolution temperature below 5 C. The phosgene solution was then placed ina 2 liter, 3-neck flask equipped with a Dry Ice condenser, a stirrer anda funnel. A solution of 164.4 g. double distilled dimer amine (0.6 eq.)in 200 ml. toluene was placed in the funnel. The diamine was prepared byhydrogenating a dimer nitrile in the presence of ammonia and methanolwetRaney nickel catalyst. The dimer nitrile was prepared from a dimerizedfat acid derived from the mixture of acids in tall oil which acidconsisted mainly of dimerized linoleic and oleic acids. The dimer aminehad the following properties: wt. percent monomer-05; Wt. percentdimer98.5; Wt. percent trimer1.0; and neut. equiv. 271.

The flask was warmed by using a heating mantle until a heavy reflux ofphosgene was observed (40-56" C.). The dimer amine solution was thenadded slowly over a 1 hour period. After the addition was complete, thereaction mixture was refluxed for an additional 2 hours. The Dry Icecondenser was replaced with a water condenser and the temperature of thesolution was raised slowly until the toluene began to reflux. Therefluxing was continued for 6 hours after which the heating wasdiscontinued and the solution allowed to cool to room temperature. Thetoluene was then removed under reduced pressure. There was obtained181.4 g. of diisocyanate having the formula:

where D is the dimeric fat radical derived from the starting dimerizedfat acid. The diisocyanate was a light brown, oily liquid.

EXAMPLE E The procedure of Example D was repeated except that thedimerized fat acid was hydrogenated prior to being converted to thedinitrile and thence to the starting dimer amine. There was obtained 179g. of saturated diisocyanate which had substantially the same propertiesas the diisocyanate of Example D but was lighter in color.

The described polyisocyanates are then reacted with oximes to form thederivatives of the present invention having the following idealized,structural formula:

where R, x and y have the meanings set forth above and R and R areselected from the group consisting of hydrogen and alkyl groups of 1 to10 carbon atoms with the proviso that the total number of carbon atomsin said groups does not exceed 10.

The oximes useful in the preparation of the "derivatives of theinvention have the general formula where R and R are as defined above.Representative alkyl groups are methyl, ethyl, propyl, isopropyl, butyl,isobutyl, pentyl, hexyl, heptyl, octyl, 2-ethyl hexyl, nonyl, decyl andthe like. Preferred oximes are those in which the total number of carbonatoms in R and R is less than about 6. Especially preferred oximes foruse in preparing the derivatives are 2-butanone oxime and acetone oxime.

The derivatives are prepared by reacting the polymeric fat acidpolyisocyanate with the oxime at temperatures of about 25 to 130 C. Itis also preferred to use substantially equivalent amounts of thereactants. An excess of the oxime can be employed and then removed atthe completion of the reaction. However, no particular advantage is seenin employing such excess. The reaction is also preferably carried out inthe presence of an inert organic solvent such as dioxane, acetone,mineral spirits, benzene or the like. The solvent is removed at thecompletion of the reaction.

The following specific description illustrates the preparation of thenew compounds of the present invention:

Example 1 Into a 500 ml. round bottom fiask equipped with a condenserwere charged 150 g. dry dioxane (dried over anhydrous sodium sulfate),150 g. of diisocyanate as prepared in Example E and 46 g. Z-butanoneoxime. The reaction mixture was refluxed for four hours (102 C.) andthen the dioxane was removed under reduced pressure mm. Hg). There wasobtained 190 g. of derivative having the formula where D is the dimericfat radical of the starting dimerized fat acid.

Example 2 Example 1 is repeated using acetone oxime (36.5 g.). There isobtained a derivative having the formula The derivatives can be used totreat leather products in general. This includes the leather from anyanimal and particularly the readily available leathers such as cowhide,pigskin, goatskin, horsehide and the like. The leather may be ordinarytanned leather or it may have been subjected to additional finishingoperations. The derivatives can also be used to treat a wide variety offibrous materials. These materials are principally cellulosic in nature,although the invention may also be used for the treatment ofnoncellulosic fibers, such as wool and other animal fibers as well assynthetic cellulosic and noncellulosic fibers, such as viscose rayon,cuprammonium rayon, cellulose acetate, nylon, polyester fibers and thelike and mixtures of fibers such as mixtures of cotton and polyesterfibers. The invention is applicable to the treatment of woven textilematerials from the above sources as well as fibrous sheets, pads, films,matsi.e., paper, and the like, laid down from such fibers even though ina nonwoven form. It is also applicable to other forms of the fibers as,for example, cel lulose sponge.

As indicated above, the derivatives of the present invention are stableat room temperature for long periods of time even in the presence ofwater. Thus in one preferred embodiment, an aqueous emulsion of the saidderivatives is prepared which emulsion also forms part of the invention.This emulsion is stable for long periods of time at roomtemperaturesi.e., by stable is meant that the derivative does not reactor lose any of its reactive isocyanate groups which groups are blockedby the reaction with the oxime. The derivative can be present in theemulsion in widely varying amounts and preferably in amounts of about.05 to 50% by Weight. The emulsion also preferably contains anemulsifying agent. The emulsion can be prepared and then stored for longperiods of time prior to use. If separation of the derivative and wateroccurs, reemulsification can be effected by simple stirring or shakmg.

The leather and fibrous material are contacted with the derivative andthen the same are heated to temperatures in the range of about to 200 C.The indicated preferred method of carrying out the contacting is toapply the described aqueous emulsion of the derivative to the leather orfibrous material. Thus the leather or fibrous material can be dipped orimmersed in the emulsion, the emulsion can be sprayed onto the surfaceor surfaces of the leather or fibrous material or the like. Of course,the derivative can be dissolved in an inert organic solvent and appliedto the leather or fibrous material. But the solvent must then be removedbecause of the flammability and other problems connected with the use oforganic solvents are encountered.

The impregnated leather or fibrous material is then heated as indicated.Such heating causes the derivative to decompose into the startingpolyisocyanate and oxime. The nature of the reaction, if any, betweenthe related polyisocyanate and the leather or fibrous material is notknown. It is, of course, possible that the isocyanate groups may reactwith the various functional groups in the leather, such as the amine andamide groups. It is also possible that the isocyanate groups may reactwith hydroxyl groups or other functional groups in the cellulosicmolecule or may react with amine groups or other functional groups innoncellulosic fibrous materials such as wool. Another possibility isthat the action which is obtained is physical in nature. A furtherpossibility is that the released polyisocyanates may form homopolymersthrough reaction between Water and the isocyanate groups to formpolwreas. Regardless of what the physical or chemical action is whichtakes place, it has been observed that the polyisocyanates do modify thephysical properties of the leather and fibrous materials. Thismodification may be in any of a number of ways, including softening,water repellency, wrinkle resistance, tear resistance and other relatedproperties.

The leather and fibrous materials can be treated with varying amounts ofthe derivatives. Relatively small quantities are effective to modifyproperties somewhat. The degree to which the properties are modifieddepends to some extent on the concentration of the derivative employed,said derivative releasing corresponding amounts of the startingpolyisocyanate on heating. In general, even minute quantities of thederivatives and thus the isocyanates produce some results. In general,for softening purposes, quantities of 0.05% and above of the derivativebased on the dry weight of the leather or fibrous material should beused. For water repellency or water proofing, higher levels of 1% on upto 5 and, in some instances, even 10% may be used. Good results areobtainable at relatively low levels for both softening and waterrepellency. The higher levels may be desirable where especially highdegrees of Water repellency or water proofness are desired. It is,therefore, an especially preferred embodiment to contact and thusimpregnate the leather or fibrous materials with from about 0.05 to 10%by Weight of the derivative based on the dry Weight of the substrate.

The following examples will serve to further illustrate the invention.

7 EXAMPLE I To a household Waring Blendor were added 196 g. water and0.4 g. emulsifying agent (Triton X-114 available from Rohm andHass-reaction product of t-octylphenol and ethylene oxidemole ratio ofabout 1 to 78). Then 4.0 g. of the derivative as prepared in Example IWas added and the resulting mixture Was blended on high blender speedfor one minute. The resulting emulsion was quite physically stable sincethere was no separation for several hours on storage at roomtemperaturei.e., 72 F. There is also no loss of isocyanate groups sincethe derivative is stable at room temperature.

EXAMPLE II A piece of birdseye cotton (8" x 18) was dipped in theemulsion of Example I, hung up to dry and then placed in an aircirculating oven for 40 minutes at 140 C. The cured piece of cotton wasthen washed using a conventional anionic detergent (Tide) and dried.Water dropped on the treated cloth after washing stayed there for morethan two hours without penetrating the cloth. The treated cloth was alsomuch softer to the feel than untreated cloth. The cloth was washed anddried five more times and such washing was found to have very littleeffect on the fine properties of the treated cloth. These same fineproperties were also obtained using a portion of the emulsion stored forone month.

EXAMPLE III Pieces of Scott #170 paper towels were dipped in theemulsion as prepared in Example I. The impregnated paper was then driedin an oven at 140 C. for 40 minutes. After drying, the treated pieces ofpaper showed definite water repellency.

EXAMPLE IV Example 111 is repeated using top-grain cowhide leather. Thedried and cured leather is water repellent and much softer than theuntreated leather.

Derivatives of my invention thus have the outstanding ability of formingaqueous emulsions without loss of reactivityi.e., isocyanate groups.They also decompose on heating at moderate temperatures to yield thestarting polyisocyanate. This is highly advantageous because the leatherand fibrous material substrates do not have to be heated todeleteriously high temperatures.

It is to be understood that the invention is not to be limited to theexact details of operation or the exact compositions shown anddescribed, as obvious modifications and equivalents will be apparent tothose skilled in the art.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A process of treating leather and fibrous materials which comprisescontacting the same With a compound having the structural formula:

H or /R spwstiaaaeo 1. 2 1

Where y is O or 1, x is an integer of 2 to about 4, R is the hydrocarbongroup of polymeric fat acids, said polymeric fat acids having beenprepared by the polymerization of monobasic, aliphatic carboxylic acidsof 824 carbon atoms, and R and R are selected from the group consistingof hydrogen and alkyl groups of 1 to 10 carbon atoms with the provisothat the total number of carbon atoms in said groups does not exceed 10and heating the resulting impregnated substrate to temperatures in therange of 100 to 200 C.

2. The process of claim 1 wherein the leather and fibrous materials arecontacted with an aqueous emulsion of the compound.

3. The process of claim 1 wherein the compound is used in an amount ofabout 0.05 to 10% by weight based on the dry weight of the leather andfibrous materials.

4. A process of treating leather and fibrous materials which comprisescontacting same with an aqueous emulsion of a compound having thestructural formula:

where x is 2, y is 1, R is ethyl, R is methyl, R is the divalenthydrocarbon group of a dimerized fat acid, said dimerized fat acidhaving been prepared by the polymerization of a mixture of fat acidsconsisting mainly of oleic and linoleic acid, and heating the resultingimpregnated substrate to temperatures in the range of 100 to 200 C.,said compound being present in the emulsion in an amount of about 0.05to 50% by weight.

5. The process of claim 4 wherein the leather and fibrous materials areimpregnated with about 0.05 to 10% by weight of the compound.

References Cited UNITED STATES PATENTS 2,303,364 12/1942 Schirm 8116.23,112,984 12/1963 Aldridge 8115.5

OTHER REFERENCES Somers: Process With New Polymers-Isocyanates and TheirModifying Effects on Other Textile Polymers, British Rayon and SilkJournal, November 1953, pp. 62 and 6 3.

Marsh: An Introduction to Textile Finishing, pp. 477-479.

Saunders et al.: Polyurethanes: Chemistry and Technology, part I, p. 82;part II, pp. 735 to 745 and pp. 750 to 7.

WILLIAM D. MARTIN, Primary Examiner H. I. GWINNELL, Assistant ExaminerUS. Cl. X.R.

